Lubricating oil composition

ABSTRACT

LUBRICANT COMPOSITION HAVING IMPROVED ANTI-FORMING PROPERTIES COMPRISING A MINERAL LUBRICATING OIL AND CONTAINING AN ANTI-FOAM AMOUNT OF PERFLUOROALKYLPOLYETHER.

Nov. 27, 1973 F. c. MCCOY ETAL 3,775,324

LUBRICATING OIL COMPOS'l'lON Filed June 1s, 1971 D I l 0 i oo I 200 7557' Hol/,05

31,775,324 Patented Nov. 27, 1973 3,715,324 y LUBRICATIN olLfcoMPoslnoN Fre'deic'C. McCoy,"Be'con, ArthurW. Godfrey, Fishkill,

and vRobert IReid, Gleuham, N.Y., assignors to Texaco Inc., New York, MY.4 I-

' Int. Cl. C10m 1/28 U.S. Cl. 252-546" 1.

ABSTRCTOF THE DISCLOSURE 'ijc'mpositmn having"`iniproved anti-foaming properties comprising a mineral lubricating oil and containing an anti-foam amount of peruoroalkylpolyether.

l BACKGROUND?FY 'THE-'INVENTION In many applicaton's',"mineral lubricating oil compositionslarre" employed' vasY functional fluids or power transniitting liuids'Examples of thisV areV automatic transmission units, pumpsa'nd"hydraulic` equipment. In such uses, the ilu'ids .are pumped or circulated at high speeds which causes the entrainm'entjfof air inthe fluid with the resultant production; of considerable amounts of foam.

Foam` in a functional lluid is highly detrimental to the @operation ofA anjautomatic transmission or a hyd'iauli'c device." The!foamingcharacteristics of oil compositions is recognized as a serious problem and industryadopted-speciiicationshavevbeen set on this lubricating oil propertilunctional iluids must pass the foam test standard'sfbefoe they* will be" qualified for hydraulic or transmission service. 'v v Th'efoam'ing tendency o f a lubricating oil composition is intensified by the presence of many additives conventionally Iemployed `in lubricating oils. 'Ihe problem is generallyfurther aggravated `bythe joint use of a number of additives inthe same lubricant composition and by increasing 'concetrations'of the additives. "The foaming tendency of many commercial functional iluids is controlled by" the'iuse of alkyl 'silicone fluids which re'elective anti-foam additives in many applications. The siliio'iie-` anti-foamadditives,. however, are not effective in some applications for functional fluids.

" SUMMARY oF THE INVENTION cosity at 100 `-Fpfrorn .50 to 2,000 containingfrom about `1Q to` 50x0p'arts per million by` weight of a perlluoroalkylpolyether-corresponding to the formula: v

in which n has a value` providingY an average molecular eiglitor theperliuoroallrylpolyether rangingfromy about 2,000 iQ 7,000.5@ w i. "FIG".V 1Y Yistitu' illustration AofA 'foam heights produced during an automatic transmission test using different antifoamant additives.

The mineral oilb'ase -fthe lubricating oil composition of the invention can bea paraflinic base, naphthenic base or a mixed paranic-naphthenic base distillate or residual Voil. Parailnic base-distillate lubricating oilfractions are preferred for the "formulation of higher quality lubricating oils'Such ailubricating'oil base will usually havel :been f subjected "to solvent refining to improven its' oxidation stability and viscosity temperature properties as "well assolveritdewaxingito A"remove wax components and thusreduceithe'f-'pour point of'ftheoil. Generally, mineral lubricating oils fractionsof interest for this in- 8 Claims vention have an SUS viscosity at 100 F. between 50 and 2,000 with the preferred mineral lubricating base oils having an SUS viscosity at 100 F. ranging from about 70 to 300.

The peruoroalkylpolyethers of the invention correspond to the formula:

in which n has aY value providing an average molecular weight for the peruoroalkylpolyether ranging from about 2,000 to 7,000. This molecular weight rangewill correspond to values for `n` ofuabout 10 to 41. The preferred peruoroalkylpolyethers are those in lwhich the average molecular weight ranges from about 3,000 to about 5,500 which molecular weights correspond to values for n of about 17 to l52, respectively. Specific examples of effective periluo'roallrylpolyethers are described below.

A EXAMPLE I A peruoroalkylpolyether having the formula:

' E-'[CF(CF,)CF,0]C,E,

and having an average molecular weight of 4,500 corresponding to a value for n of about 26. This periluoroalkylpolyether has a viscosity in centistokes at 100 F. of 85 and at 0 F. of 6,900, and an approximate boiling range at 0.8 mm. Hg of 440-485 F.

EXAMPLE II A peruoroalkylpolyether having the formula:

F-[CF (CFB )CF2O] nC2F5 and having an average molecular Weight of about 7,000 corresponding to a value for n of about 41. This perliuoroalkylpolyether has a viscosity in centistokes at 100 F. of 495 and at 210 F. of 43, and a vapor pressure at 700 Bof about 80 mm. of Hg.

Functional fluids or lubricating oil compositions of the invention will generally contain a variety of known lubricating oil additives. The peruoroalkylpolyether additive of the invention is outstanding for providing antifoam properties in functional iluids containing a variety of lubricating oil additives in substantial concentrations.

Additives which can be employed in the lubricating oil compositionof the invention include but are not limited to the alkylated diarylamines, as illustrated by U.S. Pat. 3,414,618, the zinc dithiophosphates asrillustrated by U.S. Pats-22,344,395 and 3,293,181, vthe mono-hydroxyalkyl hydrocarbyl.-thiophosphonates as illustrated by U.S. Pats. 3,135,729 and 3,272,744, the alkali metal sulfonates as illustrated by U.S. Pat. 3,537,996, the alkenyl succinic acid or anhydride polyalkylenepolyamine reaction products as illustrated by U.S. Re. 26,433 and U.S. Pat. 3,131,150 and the'polymethacrylatepolymers as illustrated by U.S. Pats. 2,737,496 and 2,471,959. The disclosures in these references are incorporatedin the present invention.

A very small concentration of the perfluoroalkylpolyethervis elective to produce an anti-foam or foamresistant lubricating oil composition. Generally, the concentration of the perliuoroalkylpolyether will range from aboutl to 500 parts Vper million. The preferred concentratin of the periluoroalkylpolyether is from about 5 to 100 parts per million.

The anti-foam properties of a series of lubricating oil composition was determined in the ASTM Foam Test, D-892. According to this test the foam volume is determined at the end of tive (5) minutes blowing with air and again after standing for an additional ten minutes in each of the three test steps or sequences, namely sequence I run at 75 F., sequence II run at 200 F. and sequence III rerun of the same sample used in sequence II and run at 75 F. The results of these tests are set out in Table I below.

tional uid compositions containing relatively high pro- TABLE I.FOAM INHIBITING PROPERTIES OF PERFLUOROALKYL POLYETHER RUN Composition (wt. percent):

Paratinic mineral oil SUS vlsc. at

100 F. of 3155.--.. 100 100 98.3 9s. 3 50 50 49.0 49. 0 Paralinic mineral oil, SUS vise. at

210 F. 011m v m A 50 50 49.0 49.0 Basie barium alkylphenolate (16.5%

barium) (50% conc. in oil) f 1.7 1.7 v v Overbased calcium sulfonate, 300

TBN (12% Ca) A 2.0 2.0 Pertluoroalkyl polyether, or Example I, p.p.m 20 20 :1 -:31.13: 20 :1::.-.232 20 ASTM foam test IIIIII IIIIII I IIIII IIIIII IIIIII IIIIII I IIIII III III/ vol. foam after5m1n.,b1ow1ng, ca -3-. 530 30 420 0 a0 0 660 600 610 a0 20 500 310 60 330 0 0 0 570 710 490 30 0 20 Vol. foam after 10 min., standing cc..-.. 0 0 0 0 0 0 420 10 590 0 0 350 20 0 10 0 0 0 490 590 440 0 0 0 The foregoing data illustrates outstanding improvements portions of additives in order to qualify the lfluids for autoin the anti-foam property of both simple and additive conmatic transmission and central hydraulic system service. taining mineral lubricating oil compositions containing the We claim: Y peruoroalkylpolyethers of the invention. 1. A lubricating oil composition consistingv essentially(l The anti-foam properties of a variety of mineral lubriof a major amount of mineral oil in the lubricating oill eating oil compositions containing relatively high concenrange having an SUS viscosity at 100 F. between 50 and trations of convention lubricating oil additives was deter- 2,000 containing from about 1 to 500 parts ,per million by mined in the Detroit Transmission Dynamic Foam Test weight of a periuoroalkylpolyether having the formula: developed by the Hydra-matic Division of General Motors F-[CF (CF 3)CF2O] l1C2F5 l Corporation. This test simulates the foaming caused in in which n has a value providing an average molecular commercial automatic transmissions through the use of a weight for the peruoroalkylpolyether ranging from about pump, a circulating system, a heater and an agitating 2,000 to 7,000. device. The test fluid is maintained at temperature of 2. A lubricating oil composition according to claim 1 275 F. The uids fail this test if the foam height exceeds in which said perliuoroalkylpolyether has an average V 1% (three-eighths) of an inch or if the foam collapse time molecular weight ranging from about 3,000 to 5,500. exceeds (23) twenty-three seconds. The results of this test 3. A lubricating oil composition according to claim 1 are set out in Table II below which compares the antiin which said perlluoroalkylpolyether has an average mo,- foam properties of the lubricants of the invention with lecular weight of about 4,500. similar lubricating oil compositions. 4. A lubricating oil composition according to claim 1 TABLE II f Run Composition (wt. percent):

1. Solvent refined naphthene base mineral oll having an SUS viscosity at 100 F. of 50.- 42.00 45.00 42. 00 42.00 42.00 45.00 42.00 2. Paranicmineral oil having an SUS v'lscosityat 100 F. 01100 44.74 41.00 44.74 44.74 45.44 41.00 45.44 3. Polymethacrylate viscosity index improver 8.00 8.00 8.00 8.00 8.00 8.00 8.00 4. Additive concentrate 15.20 15.00 15. 26 15.20 14.50 26.00 14.50 5. sinconeso1ut10n,p.pm 4150 1150 1150 1330 1150 .1150 f 6. Periluoroalkyl polyether of Example 1, p. m 25 100 100 1 Blend oi conventional lubricant additives.

2 Commercial lubricant additive blend.

i Second blend of conventional lubricant additives. 77 12 wt. percent solution in kerosene of silicone fluid of 100,000 cs. at 77 i? .12 wt. percent solution in kerosene of silicone fluid of 60,000 cs.at 5.6 wt. percent solution in kerosene of silicone uld of 1,000,000 cs. at 77 F. with dispersant. m

1As asolution 10 grams diluted to 100 g. in trliuorotrlchloroethane.

D.T.D. FOAM TEST 275 F. foam height, in l Zio Collapse time, sec 37 .55 l*3 7 30 in which said peruoroalkylpolyether has an average mo-I lecular weight of about 2,000.

5. A lubricating oil composition according to claim I containing in addition from about 0.01 to 20 weight per-V cent of a foam-promoting mineral lubricating oil additive;

6. A lubricating oil composition according to claim 1 containing from about 0.1 to 10 percent of a polymethl' acrylate viscosity index improver.

7. A lubricating oil` composition according to claimvl containing from about 5 to 100 per "millionof'salid.l

of this test are illustrated in the accompanying Figure 1. peruoroalkylpolyether.

5 6 8. A lubricating oil composition according to claim 1 2,515,115 7/ 1950 Davis et al. 252--54.6 in which said mineral oil has an SUS viscosity at 100 F. 2,915,471 12/ 1959 Lorensen 252-54.6 X from 70 to 300' PATRICK P. GARVIN, Primary Examiner References Cited 5 UNITED STATES PATENTS U's' Cl' X-R' 3,445,392 5/1969 Gumprecht et al. 252-54 252-54 334 42'7 78 3,597,359 8/1971 Smith 252-78 

